Investigating the long-term effects of air pollution on soil properties in the vicinity of the Arnot power station

• Main Author: Reid, Joanne Lynne
• Format: Others
• Language: en
• Published: 2008
• Subjects: acid deposition; air pollution; coal-fired power station; soil acidity; sulphates
• Online Access: http://hdl.handle.net/10539/4875

A study was conducted in 2006 to investigate the long-term effects of air pollution on soil properties in the vicinity of the Arnot power station, Mpumalanga, South Africa. Fifteen sites were re-sampled and the soil chemical properties compared to baseline data gathered in 1996, resulting in a ten year period after which changes in soil properties were investigated. A spatial gradient was incorporated into the study in order to better understand the deposition of pollutants with increasing distance from the power station. The study indicates that long-term acidic deposition has led to detectable changes in soil chemical properties. Three chemical properties, namely the concentrations of calcium and magnesium in both the topsoils and the subsoils, as well as the effective cation exchange capacity in the subsoils showed a significant increase since 1996. However, five soil chemical properties, namely soil pH (K2SO4), the concentration of hydrogen and aluminium and total sulphur in both the topsoils and the subsoils, as well as extractable sulphate in the topsoils and soluble sulphate in the subsoils, all show that the soils have become more acidic over the ten years. The acidic components in the soil override the basic components, as shown by the ratio of basic cations to acidic cations in the soils. The spatial gradient generally indicates that at approximately 8 km from the power station, there is a decrease in the concentration of acidic soil properties and one explanation for this may be a reduction in the acidic components of atmospheric deposition at this site. However, this needs further investigation. Two significant relationships with distance were found, namely a significant negative relationship with soluble sulphate and a significant positive relationship with acid neutralising capacity. This research will form part of a database for other long-term monitoring programmes and will allow data to be compared to other data from this area of research. It will also provide information to important industry leaders such as Eskom.